The collection and analysis of data on cancer in human populations and on the end results of treatment are the major functions of this project. This includes consultations and advice on methodological problems, development of improved statistical procedures for the analysis of observations on human populations, and active collaboration in the collection and analysis of data in specific projects. Particular emphasis is being placed on evaluating detailed descriptive systems for Extent of Disease and studies of prognostic factors in cancer of the breast, Hodgkin's Disease, and other forms of malignant neoplasm. This project also involves participation in international studies designed to capitalize on differences among countries with respect to cancer incidence and survival in attempting to further clarify the relationship between etiological factors and prognosis.